Cheomseongdae Astronomical Observatory

Cheomseongdae is a stone tower well known as the oldest astronomical observatory in the East. Cheomseongdae is about 9 meters in height and looks like a round bottle. This stone tower was made by laying 27 stones in a neat pile on the square foundation stone and by putting a square stone on the piles like a lid. The tower has a 1-meter by 1-meter window facing south. The tower’s architecture is highly valued for the beauty of its elegant curves and the exquisite harmony between a square and a circle.

This stone structure is a beautiful combination of straight lines and curves, and was designated as National Treasure No.31 on December 20th, 1962.  Cheomseongdae was built in a cylinder shape with stones 30cm in diameter. 362 stones were piled up to make 27 levels. 4.16m up from the bottom there is a 1㎡ square entrance and a space to hang a ladder under it.  The inside is filled with soil up to the 12th level, and the 19th, 20th, 25th, and 26th levels all have long rocks hanging on two areas, shaped as the Chinese letter (jeong).  It stands 9.17m high and the base stone on each side measures 5.35m.